Those money problems in immortal are unusual. The only thing I can think of apart from the list above is to build roads at the RIGHT time, not too soon not too late. Rule of thumb, the number of road tiles at least equal to the size of the city is going to. Also, prebuild the roads but don't finish them until expo is the right size. By this I mean if building a road take 2-3 turns, do the first 1-2 turns and then on to next tile, that means free pre built road segment, so when it is the right time you can build fast. Apart from that, I cannot think of other advice. In immortal AIs usually have plenty of gpt and cash. Maybe your terrain totally awful?